1. Field of the Invention
The present invention relates to an X-ray imaging apparatus that picks up an image of a subject. In particular, the present invention relates to an X-ray imaging apparatus that suitably adjusts the size of an X-ray photographic image when outputting the image to a plurality of output devices and a method for outputting the X-ray images.
2. Description of the Related Art
As an imaging technique for X-ray imaging apparatus for medical diagnosis, techniques of digitally detecting X-rays and generating X-ray images have been achieving widespread use instead of an X-ray photographic method in which an intensifying screen and a film are used in combination at an X-ray detection unit. As an example of a typical digital X-ray imaging apparatus, there is a digital X-ray imaging apparatus in which a flat-panel sensor is used as a detection device. As X-ray imaging acquisition methods used in digital X-ray imaging apparatus using a flat-panel sensor, there are: a method in which solid-state imaging devices, which are sensitive to X-rays and convert the detected X-rays into electric signals corresponding to the intensity of the X-rays to output the signals, are used, the analog signals from the solid-state devices are converted to digital signals, and the signals are captured for imaging; and a method in which a phosphor, which absorbs the energy of X-rays and emits fluorescence corresponding to the intensity of the energy, and photoelectric conversion elements, which are sensitive to visible light and convert the visible light into electric signals corresponding to the intensity of the visible light, are combined together, the analog signals from the photoelectric conversion elements are converted to digital signals, and the signals are captured for imaging.
Such digital X-ray imaging apparatuses are each constituted by an inspection module and a control unit for controlling the inspection module and an X-ray generator. The inspection module includes a detection device that detects an electrical quantity that corresponds to an X-ray transmission dose and that converts the electrical quantity to a digital quantity. The control unit subjects a captured image to various kinds of correction processing and image processing to generate an X-ray digital image for diagnosis by a doctor. The generated digital image is output from a printer onto a film, or is sent to a storage and displayed on a monitor as necessary, following which the digital image is observed by a doctor.
However, since the size of each film is predetermined, depending on a subject's height and weight, there are cases where an observation region in an image does not completely fit onto a film. In such a case, as described in Japanese Patent Laid-Open No. 2000-115513 (hereinafter referred to as “Document 1”), the orientation of a film is changed, extraction processing is carried out to fit a necessary region in an observation region onto a film, or the entire observation region is reduced so that the region fits onto a film. Of the above methods, the method of reducing the entire observation region to fit the region onto a film is generally not used, because reduction ratios differ depending on the sizes of observation regions, so it is hard to make diagnoses, and this may lead to misdiagnoses. In cases where an X-ray photograph is used for diagnosis, an output mode is used that is either life-size output in which an image on a sensor is output in actual size or fixed reduction ratio output in which an image is output at a fixed reduction ratio.
In a case where an observation region has not completely fitted onto a film even with a film's orientation changed in these output modes, a necessary region has been extracted from the observation region, and has been output to a printer and a storage in a diagnostic image processing work station. In such a method, however, the size of an image to be output to the storage is limited to an output size of the printer, and an image across the entire observation region cannot be obtained when having called up the image on an X-ray interpretation work station. Because of this, in a case where there has been an informative diagnostic point outside the extracted region, there is a possibility that the point was missed. To solve such problems, an operator has to call up an image after the image was output to the printer, change the size of the image, and output the image to the storage again. Therefore, imaging operation becomes complicated, and thus operation efficiency worsens.
Japanese Patent Laid-Open No. 2006-296954 (hereinafter referred to as “Document 2”) states that an irradiated region is output to a storage and that an extracted image is output to a printer. In Document 2, however, there is no description of performing a suitable extraction adjustment on an image for image output to the storage and the printer. In cases where an image size is determined by image viewer specifications and where only a fit display mode is enabled, the output size is sometimes limited even in the case of output to a storage. In those cases, there has been a problem in that in a case where it is impossible to subject an image to be output to a storage to extraction adjustment as in Document 2, an error occurs in executing the output to the storage, and it is, therefore, impossible to output the image. It should be noted that “fit display” means that an image is displayed to the maximum extent in a predetermined image display region with the aspect ratio of the displayed image maintained.